Base= 12m
Height= 5m
By Pythagoras theorem we know that,
Hypotenuse²
=Base² + Height²
Hypotenuse ²
= 5²+12²
= 25+144
=169
Hypotenuse= √169
= 13 m
Here hypotenuse is the length of ladder.
Therfor,
Length of the ladder is 13m
You could use a graph of above scene if you need.
It's simple , so Iam not trying that.You can do that.
Hope this helps.
Good luck.